Water Trapped in Soft Nanolayers Reveals a Hidden Glassy State

Water confined inside extremely thin layers of a lipid-like material has revealed a low-temperature state that is normally hidden by rapid ice formation, according to research reported by Phys.org and conducted by an international collaboration using facilities operated by the Australian Nuclear Science and Technology Organisation. In ordinary conditions, water tends to form crystalline ice before scientists can observe its transition from a liquid into a glass. A glass is a disordered solid-like state formed when a material’s particles become effectively locked in place without arranging themselves into a crystal. To avoid the usual crystallization process, the researchers placed small quantities of water inside nanoscale layers of phytantriol, a molecule that forms lipid-like membranes. This “soft nanoconfinement” kept the water from turning into ordinary ice as temperatures fell below its normal freezing point. The team found that the confined water entered a glassy state across a broader temperature range than previously understood. Neutron experiments indicated that the movement of hydrogen atoms—and therefore the motion of water molecules—changed substantially between roughly -35°C and -20°C. At these temperatures, the water became glassy while the surrounding membranes remained mobile and fluid. Several techniques were combined to examine the material’s structure and molecular motion. X-ray scattering experiments at the Australian Synchrotron tracked the confined water and its surroundings at temperatures as low as -120°C. Neutron measurements at the Australian Centre for Neutron Scattering were particularly useful because neutrons are sensitive to hydrogen, allowing researchers to distinguish water’s behavior within the more complex membrane system. The study also included work at the Soleil Synchrotron in France, low-temperature microscopy, nuclear magnetic resonance spectroscopy and computer simulations. Deuteration helped separate signals from the water and the surrounding lipid material. The findings, published in Nature Communications, may be relevant to cryopreservation, food-freezing methods and efforts to understand water confined within living cells. The work does not suggest that everyday water remains liquid at these temperatures; instead, it examines how water behaves when its crystallization is prevented by nanoscale confinement.